Increased expression of the gene encoding stearoyl-CoA desaturase 1 in human bladder cancer.

Bladder cancer is a common disease and a significant cause of death worldwide. There is thus great interest in identifying a diagnostic and prognostic biomarker, as well as gaining an understanding of the molecular basis of bladder cancer. Stearoyl-CoA desaturase 1 gene (SCD1) is highly overexpressed in many human cancers. However, the expression of SCD1 has not yet been investigated in patients with bladder cancer. Here, we document that (a) the SCD1 is highly overexpressed in human bladder cancer; (b) high expression of SCD1 is more frequently observed in the late stage of disease and patients with lymph node metastasis; (c) bladder cancer patients with a higher SCD1 mRNA level have a poorer survival rate than those with normal SCD1 expression. Overall, this is the first report to indicate an association between SCD1 mRNA level and clinical indicators of human bladder cancer. Our study has provided evidence supporting the potential role of SCD1 as a biomarker for human bladder cancer prognosis.

The increase of serum chemerin concentration is mainly associated with the increase of body mass index in obese, non-diabetic subjects.

BACKGROUND: Chemerin is a newly discovered adipokine, whose circulating concentration is increased in obesity. AIM: To elucidate whether the increased circulating chemerin concentrations in obese subjects are associated with the increase of fat mass, the increase in chemerin gene expression in adipose tissue or both. MATERIAL/SUBJECTS AND METHODS: Serum chemerin concentrations in 20 non-obese healthy volunteers and 21 non-diabetic obese subjects were measured using ELISA. Chemerin mRNA and chemerin protein levels in visceral and subcutaneous adipose tissues of obese subjects were analyzed by Real-Time PCR and Western blot respectively. RESULTS: We found that the serum chemerin concentrations were significantly higher in obese subjects than in controls and positively correlated with BMI, fat mass and body mass. Moreover serum chemerin concentrations were correlated positively with serum CRP concentrations independently of BMI. No correlation was found between the chemerin mRNA and chemerin protein levels in visceral and subcutaneous adipose tissues and BMI, fat mass, or body weight. Likewise, there was no correlation between the serum chemerin concentrations and the levels of chemerin mRNA and protein in adipose tissue of obese patients. Multiple regression analysis suggests that BMI was the main predictor of serum chemerin concentration. In contrast to chemerin, both serum leptin concentrations and adipose tissue leptin mRNA levels positively correlated with BMI. CONCLUSIONS: The results presented here indicate that serum chemerin concentrations correlated with BMI, whereas chemerin mRNA levels in adipose tissue did not. Thus the elevated circulating chemerin concentration in obese, non-diabetic patients was mainly associated with the increased BMI.

Bioenergetics of fish spermatozoa during semen storage.

This mini-review focuses on changes in ATP and creatine phosphate concentrations in fish sperm under storage conditions. The storage of catfish sperm at 4 degrees C leads to ATP depletion and decreased sperm motility. The rate of intracellular ATP depletion can be diminished through the addition of energetic substrates to the sperm storage medium, with lactate + pyruvate being the most efficient substrates for maintaining ATP concentrations in catfish sperm. The decrease in ATP concentration is closely associated with increases in AMP and hypoxanthine content. In contrast to catfish sperm, carp sperm is able to maintain intracellular ATP concentration close to the physiological level during storage. Collectively, these results suggest that fish species differ in terms of the energy metabolism of their spermatozoa and that the semen storage medium must be carefully selected for a particular fish species so as to maintain the ATP concentration and adenylate energy charge close to physiological values as long as possible.

Decrease in serum protein carbonyl groups concentration and maintained hyperhomocysteinemia in patients undergoing bariatric surgery.

BACKGROUND: Human obesity is associated with oxidative stress but the factors contributing to the increase of reactive oxygen species (ROS) production remain unknown. We evaluated the association between serum homocysteine concentration, which may increase ROS production, and serum protein carbonyl groups concentration before and after bariatric surgery. METHODS: Serum protein carbonyl groups and serum homocysteine concentrations, as well as obesity markers, were compared in 18 obese patients before and 6 months after bariatric surgery. Ten healthy individuals with normal body mass index (BMI) served as controls. RESULTS: Before bariatric surgery, obese patients displayed approximately 50% higher serum protein carbonyl groups concentration than control subjects. After surgery, serum protein carbonyl groups concentration decreased and matched values observed in controls. Serum homocysteine concentration was also elevated in obese patients, but in contrast to protein carbonyl groups, did not change after surgery. The body weight, BMI, HOMA-IR, serum leptin, triacylglycerols, LDL/HLD cholesterol ratio, insulin, and glucose concentrations were higher in obese patients as compared to controls, and decreased after bariatric surgery. CONCLUSIONS: This study demonstrates that bariatric surgery has protective effect on oxidative protein damage and improves several laboratory parameters including serum lipid concentration and insulin resistance. However, bariatric surgery does not cause a decrease in serum homocysteine concentration, a risk factor for the development of cardiovascular diseases. Collectively, the results presented in this paper suggest that serum homocysteine concentration is not directly associated with oxidative stress in obese patients after bariatric surgery.

Liquid chromatographic/mass spectrometric procedure for measurement of NAD catabolites in human and rat plasma and urine.

Monitoring level of the metabolites of the coenzyme NAD such as nicotinamide and its oxidized and methylated derivatives is important due to therapeutic applications of these compounds and monitoring of oxidative stress. We evaluated feasibility of using HPLC with electrospray ion-trap mass detection for single run separation and quantitation of all the NAD metabolites. We achieved good separation and retention of all the metabolites of interest using reversed-phase with ion-pairing. Single ion monitoring or tandem MS were used for detection and quantitation of the specific compounds with good linearity. The method was able to detect all the physiological metabolites in plasma samples of rats and humans or in urine. However, full validation is necessary before this method could be routinely applied.

Pharmacological doses of triiodothyronine upregulate lipogenic enzyme gene expression in rat white adipose tissue.

Triiodothyronine (T (3)) is known to increase liver lipogenic enzyme gene expression both in vivo and in tissue culture. Conflicting results have been reported on the effect of T (3) on lipogenic enzyme gene expression in white adipose tissue. The results presented in this paper indicate that administration of pharmacological doses of T (3) in rats leads to increased fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), ATP-citrate lyase (ACL) and malic enzyme (ME) activity in white adipose tissue. The increase in lipogenic enzyme activity was associated with increased FAS, ACC, ACL and ME mRNA levels. The response was dose-dependent. Activity of lipogenic enzyme and the lipogenic enzyme mRNA levels were positively correlated to serum T (3) concentration. The in vivo effect of T (3) on lipogenic enzyme gene expression could be reproduced in primary white rat adipocyte culture. In conclusion, the results presented in this paper indicate that T (3) exerts a stimulatory effect on lipogenic enzyme gene expression in white adipose tissue both in vivo and in tissue culture. Significant effects of T (3) on lipogenic enzyme gene expression were only observed in the presence of relatively high (pharmacological) concentrations of the hormone.

Leptin and age-related down-regulation of lipogenic enzymes genes expression in rat white adipose tissue.

The age-related inverse relationship between gene expression of lipogenic enzymes and leptin gene expression as well as inhibitory effect of leptin on lipogenic enzyme's gene expression suggest that leptin could be responsible in part for the low rate of lipogenesis in white adipose (WAT) of old rats. Based on the data published recently we propose a model for the direct inhibitory effect of leptin on lipogenesis. This model may explain the age-related decrease of lipogenic activity in WAT. It is likely that despite of higher concentration of noradrenaline (which inhibits leptin gene expression in WAT) in old animals, the age-dependent decrease of beta-adrenergic receptor density in rat adipocytes may lead to the increase of leptin gene expression and to the increase of WAT leptin concentration. High concentration of leptin in adipose tissue decreases sterol regulatory element binding protein-1 (SREBP-1) gene expression by paracrine and/or autocrine action on adipocyte, which leads to the decrease of SREBP-1c level (mature form). The suppression of SREBP-1c synthesis causes a decrease of lipogenic enzyme's gene expression which consequently results in lower rate of fatty acid synthesis in WAT. This model does not exclude the indirect, via hypothalamus (by decreasing food consumption), inhibitory action of leptin on WAT lipogenesis. Therefore, it is likely that leptin exerts its inhibitory effect on WAT lipogenesis both directly at the level of adipocytes, and indirectly through hypothalamus by decreasing food intake. The inhibitory effect of of high leptin concentration on lipogenesis in WAT of old rats could prevent over-accumulation of triacylglycerols in adipocyte, and by this way could protect against further development of the fat mass.

The effects of weight cycling on serum leptin levels and lipogenic enzyme activities in adipose tissue.

Weight cycling is one of the widely used weight reduction strategies; however, the adverse effects of this method include regaining significant amounts of weight. The molecular mechanisms underlying weight gain following cycles of dietary deprivation and refeeding are still poorly understood. One of the possibilities is that repeated loss and gain of weight may promote fat deposition in adipose tissue. To test this hypothesis we investigated serum leptin levels and lipogenic enzyme activities in white adipose tissue (WAT) of male Wistar rats during 12 days of ad libitum feeding following multiple cycles of alternating food deprivation and refeeding. Rats subjected to eight cycles of food deprivation and refeeding (MFR group) showed significantly decreased circulating leptin levels when compared with control rats (nearly 50% decrease in leptin levels, P < 0.01). Throughout 12 days of ad libitum feeding, serum leptin levels increased modestly but remained significantly (24%, P < 0.05) lower than control levels. Fatty acid synthase (FAS) and malic enzyme (ME) activities (chosen as representatives of enzymes directly involved in fatty acid synthesis) were found to be considerably higher in WAT of MFR rats refed for 3 days in comparison to control rats, and remained elevated even after 12 days of refeeding. These observations suggest that the elevation of lipogenic enzyme activities induced by multiple cycles of dietary deprivation followed by refeeding persists for several days, markedly increasing the lipogenic capacity of adipose tissue, which, accompanied by a decrease in circulating leptin levels, may promote weight gain.

The effect of N-methyl-2-pyridone-5-carboxamide--A nicotinamide catabolite on poly ADP-rybosylation and oxidative stress injury in endothelial cells.

This study evaluated the effect of nicotinamide (NA) and its endogenous metabolite 2PY (N-methyl-2-pyridone-5-carboxamide) on the activity of poly (ADP-ribose) polymerase (PARP) and on peroxynitrite-induced injury in endothelial cells. 2PY and NA inhibited isolated PARP with half-maximal constants of 0.53 mM and 0.025 mM, respectively. Exposure to peroxynitrite caused a decrease of the NAD pool in cultured endothelial cells to below 10% of initial level. Addition of 2PY or NA provided partial protection from peroxynitrite-induced NAD depletion, with NA being more effective. 2PY and NA also provide protection from ATP depletion. We conclude that NA as well as 2PY protect from oxidative stress injury in endothelial cells by inhibition of PARP and protection from NAD depletion. This, in turn, protects energetics, allowing maintaining cellular ATP.

Increased activity of glycerol 3-phosphate dehydrogenase and other lipogenic enzymes in human bladder cancer.

Common molecular changes in cancer cells are high carbon flux through the glycolytic pathway and overexpression of fatty acid synthase, a key lipogenic enzyme. Since glycerol 3-phosphate dehydrogenase creates a link between carbohydrates and the lipid metabolism, we have investigated the activity of glycerol 3-phosphate dehydrogenase and various lipogenic enzymes in human bladder cancer. The data presented in this paper indicate that glycerol 3-phosphate dehydrogenase activity in human bladder cancer is significantly higher compared to adjacent non-neoplastic tissue, serving as normal control bladder tissue. Increased glycerol 3-phosphate dehydrogenase activity is accompanied by increased enzyme activity, either directly (fatty acid synthase) or indirectly (through ATP-citrate lyase, glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and citrate synthase) involved in fatty acid synthesis. Coordinated upregulation of glycerol 3-phosphate dehydrogenase and lipogenic enzymes activities in human bladder cancer suggests that glycerol 3-phosphate dehydrogenase supplies glycerol 3-phosphate for lipid biosynthesis.

Differential effect of long-term food restriction on fatty acid synthase and leptin gene expression in rat white adipose tissue.

Long-term food restriction (85%, 70% and 50% of ad libitum energy intake for one month) induced a substantial fall in serum leptin concentration and leptin mRNA levels in epididymal white adipose tissue in rats. Surprisingly, this suppression was not reversed by refeeding ad libitum for 48 h. The reduction in serum leptin concentration and leptin mRNA level did not strictly correlate with reduction in fat or body mass. Unlike serum leptin concentration and epididymal adipose tissue leptin mRNA levels, fatty acid synthase activity, fatty acid synthase protein abundance and fatty acid synthase mRNA levels increased significantly in white adipose tissue after refeeding rats subjected to food restriction. The increase in serum insulin concentration was observed in all groups on different degrees of food restriction and refed ad libitum for 48 h compared to controls. A decrease in serum insulin concentration was found in the rats not refed before sacrifice. Long-term food restriction did not significantly affect serum glucose concentrations in either refed or non-refed rats. The data reported in this paper indicate that there is no rapid rebound in serum leptin concentration or leptin gene expression in contrast to the increase in serum insulin concentration and fatty acid gene expression in white adipose tissue of rats refed ad libitum after one month's food restriction.

Increased rate of cholesterologenesis--a possible cause of hypercholesterolemia in experimental chronic renal failure in rats.

Hypercholesterolemia plays an important role in the lipid abnormalities in chronic renal failure (CRF). It is thought to contribute to both a progression of renal failure and atherosclerosis. Despite intensive research, the etiopathogenesis of hypercholesterolemia in CRF patients is still obscure. The present study was designed to evaluate the possible role of cholesterol overproduction in the development of hypercholesterolemia associated with experimental CRF. We found that plasma total cholesterol and cholesterol distributed in VLDL, LDL and HDL concentrations were significantly enhanced in CRF rats. Simultaneously, the rate of liver cholesterol biosynthesis in vivo (measured by determining the incorporation of tritium from tritiated water intraperitoneally injected into cholesterol ), liver microsomal 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity and liver HMG-CoA reductase mRNA presence were elevated. Significant increases in activity of liver malic enzyme, glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, NADPH-producing enzyme (required for cholesterol synthesis) have also been observed in CRF rats. In conclusion, the increased rate of liver cholesterol biosynthesis due to increase of HMG-CoA reductase and NADPH-producing enzyme gene expression could be one of the possible causes of hypercholesterolemia in CRF animals.

Lipogenesis in experimental chronic renal failure in rats.

Hyperlipidemia is a common occurance in patients with chronic renal failure (CRF) and has been the subject of many clinical and experimental studies. Despite this, the role of lipogenesis in the development of hyperlipidemia is still obscure. The present study is based on a rat model of CRF involving a two-stage subtotal nephrectomy. In this study, we measured the activity of fatty acid synthase (FAS). This is the rate-limiting enzyme of lipogenesis and is present in liver and white adipose tissue (WAT). Using isotopic methods, we also determined the rate of lipogenesis in vivo in liver and WAT. In both liver and WAT, the results of the analyses were similar. In the uremic rats, there was a tendency for the FAS activity to rise. However, the difference was not statistically significant. Furthermore, there was no increase in the rate of lipogenesis in vivo in either tissue. In summary, the results of our study confirm the thesis that lipogenesis does not play a role in the development of hypertriglyceridemia seen in an experimental CRF in rats.

[Adenine reutilization as a cause of increased ATP concentration in erythrocytes of patients with chronic renal failure]. / Reutylizacja adeniny jedna z przyczyn wzrostu stezenia ATP w erytrocytach pacjentów z przewlekla niewydolnoscia nerek.

Abnormalities of adenine nucleotide metabolism are observed in erythrocytes of patients with chronic renal failure (CRF) and the elevated ATP concentration is the most impressive one. In humans, adenine and/or adenosine reutilization is the only source of purine moiety used to erythrocyte adenine nucleotide synthesis. In the present study we have focused on the role of adenine as a substrate for the intraerythrocyte ATP production. 10 patients with CRF and 10 healthy volunteers (control group) were included into the study. Using HPLC, the measurements were performed in plasma and erythrocyte extracts. We observed a few fold higher adenine concentration in both plasma and erythrocytes of patients with CRF when compared with control group. There was also elevated an intraerythrocyte ATP concentration in the studied group of patients. Moreover, we have found a positive correlations between a) plasma creatinine concentration and plasma adenine concentration, b) plasma creatinine concentration and erythrocyte adenine concentration, c) plasma adenine concentration and intraerythrocyte ATP concentration. It appears that increased adenine reutilization could be a principle reason of the increased ATP synthesis in erythrocytes of patients with CRF.

The age-related differences in obese and fatty acid synthase gene expression in white adipose tissue of rat.

To determine if the age-dependent increase of adiposity is directly related to altered obese (ob) and fatty acid synthase (FAS) gene expression, we assessed an adiposity index, leptin and FAS mRNA levels, FAS activity in perirenal adipose tissue and serum leptin concentration in rats aged 1, 2, 3, 6 and 20 months. The results indicate that there are two distinct phases of changes in perirenal white adipose tissue leptin mRNA level and serum leptin concentration. The first phase, between 1 and 3 months of the animals' lives, was characterized by a strong positive correlation between adiposity index and leptin mRNA level as well as serum leptin concentration. In the second phase (over 3 months) no significant changes of leptin mRNA and serum concentration occurred. A close correlation between the age-induced increase of leptin mRNA abundance and serum leptin concentration and the age-induced suppression of FAS gene expression in the same tissue was observed. This suggests that the changes of FAS gene expression occur in response to serum leptin concentration and that in mature rats the high level of ob gene expression and consequently the high leptin concentration protect the white adipose tissue cells against fat overload by two independent mechanisms: (a) preventing an increase of food intake through the leptin action on the hypothalamus; (b) inhibiting FAS gene expression and consequently decreasing the rate of lipogenesis.

Increase of lipogenic enzyme mRNA levels in rat white adipose tissue after multiple cycles of starvation-refeeding.

Recently, we have found that despite the significant reduction of body weight after multiple starvation-refeeding cycles, white adipose tissue (WAT) exhibits surprisingly high rates of lipogenesis and lipogenic enzyme activities. The purpose of this study was to determine the response of WAT lipogenic enzyme mRNAs of rats subjected to multiple cycles of 3 days fasting and 3 days of refeeding. Despite the body weight reduction, significant increase of lipogenic enzymes (ie, fatty acid synthase [FAS], acetyl-coenzyme A [CoA] carboxylase [ACC], adenosine triphosphate (ATP)-citrate lyase [ACL], NADP-linked malic enzyme [ME], and glucose 6-phosphate dehydrogenase [G6PDH]) mRNAs in WAT was found after multiple cycles of starvation-refeeding of rats on standard laboratory diet. These findings, together with the results published recently, indicate that multiple cycles of starvation-refeeding cause the increased lipogenesis in WAT by upregulation of the lipogenic enzymes gene expression.

The decrease of rat postprandial plasma triacylglycerol concentration after multiple cycles of starvation-refeeding.

The effect of multiple cycles of starvation-refeeding on rat body weight and on plasma lipid concentration was studied. After 1 cycle of starvation-refeeding, the rat body weight did not change significantly; however the postprandial plasma triacylglycerol concentration decreased approximately 2-fold as compared to rats fed ad libitum. After 8 cycles of starvation-refeeding, both rat body weight and plasma triacylglycerols concentration decreased. In contrast, the plasma cholesterol (both total and HDL cholesterol) concentration did not change appreciably either after 1 or 8 cycles of starvation-refeeding as compared to control. Although the postprandial plasma triacylglycerol concentration decreased in both groups (i.e. after 1 and 8 cycles of starvation-refeeding), this phenomenon appears to last longer after 8 cycles of starvation-refeeding. The epididymal white adipose tissue weight decreased after both 1 and 8 cycles of starvation-refeeding. After 1 cycle of starvation-refeeding followed by 3, 6 and 9 days of ad libitum feeding, the epididymal white adipose tissue weight increased progressively, reaching the control value at day 9. In contrast, after 8 cycles of starvation-refeeding followed by 9 days of ad libitum feeding, the epididymal white adipose tissue weight did not reach the control value. These results suggest that dieting is associated with body and adipose tissue weight loss as well as with the decrease of plasma triacylglycerol concentration. Furthermore, our results suggest that better maintenance of low adipose tissue weight and low plasma triacylglycerol concentration may be achieved after multiple cycles of starvation-refeeding.

Low leptin mRNA level in adipose tissue and normoleptinemia in experimental chronic renal failure.

BACKGROUND: Anorexia and weight loss frequently accompany chronic renal failure (CRF). Although multiple metabolic changes occur during CRF, a bulk of evidence indicates that the decrease in caloric intake plays a major role in CRF-induced weight loss. Recently, it has been suggested that elevated plasma leptin concentrations could contribute to anorexia and to downregulation of leptin gene expression in CRF patients. However, in some CRF patients, plasma leptin concentrations have been found to be lower than one could expect. Thus we assumed that inhibition of leptin synthesis plays an important role in the regulation of plasma leptin concentrations in CRF patients. METHODS: To test this assumption, the leptin mRNA level in rat white adipose tissue from ad-libitum-fed control (sham operated), pair-fed control (sham operated) and rats with experimentally induced CRF has been measured by Northern blotting analysis. In addition, serum leptin concentration (by radioimmunoassay) was determined in all three groups of animals. RESULTS: The results of the present study indicate that in experimental CRF the leptin mRNA level is decreased by about 50% as compared to the sham-operated animals (ad-libitum-fed and pair-fed controls). The mean serum leptin concentration in CRF rats was essentially similar to the leptin concentration in sham-operated ones. CONCLUSION: The data obtained suggest that in CRF animals the serum leptin concentration might be affected not only by the decrease in leptin removal in the kidney, but also by the decrease in leptin secretion from adipose tissue. Furthermore, the results of the study suggest that leptin may be only one of many factors involved in the pathogenesis of malnutrition associated with CRF.